The present invention is directed, in general, to an injection molding machine with a moving rotary device.
WO 01/010624 discloses a two-platen horizontal injection molding machine with a fixed platen and a moving platen, which moves along columns, as well as a rotary device which is provided for injection molding tools and arranged between the two platens, and which is displaceable parallel to the longitudinal machine axis and rotatable about a vertical axis. The rotary device includes a base plate which can be moved by a drive assembly in the longitudinal machine direction, a turntable which is arranged on the base plate and which can be rotated by second drive means about the vertical axis. For displacing the base plate, hydraulic actuators are provided which are attached, on one hand, on the base plate and, on the other hand, in the machine bed and/or on the fixed platen. This type of horizontal injection molding machine is applicable for smaller sized machines. However, when large-sized horizontal injection molding machines are involved which have correspondingly sized rotary device and heavy mold halves, tilting moments are encountered during acceleration and deceleration of the base plate due to their mass inertia which have to be compensated. The base plate is thus guided on linear guides which must be correspondingly dimensioned in cross-section, for example a dovetail cross-section. With increasing size of the horizontal injection molding machine, the tilting moments to be absorbed also increase; however, the required linear guides with a dovetail cross-section are relatively expensive and not available for very large horizontal injection molding machines.
WO 03/013824 A1 discloses a two-platen horizontal injection molding machine wherein a reversing plate adapted to receive mold halves of injection molding tools and operating as rotary device for the injection molding tools is stationarily supported for rotation about a vertical axis in two directions in a closed solid support frame or in a C-shaped support frame which is open to one side, with the platens being movable relative to the support frame.
The document JP 62060618A discloses a two-platen horizontal injection molding machine with a rotary device which is provided for injection molding tools and arranged between the two platens and which is displaceable parallel to the longitudinal machine axis and rotatable about a vertical axis. In this horizontal injection molding machine, the rotary device has upper and lower support blocks which are supported and guided on the columns. A mold half carrier with an upper and a lower pivot pin arranged on an axis is received for rotation between the support blocks. For moving the mold half carrier along the longitudinal machine axis, hydraulic actuators are provided between the fixed platen, on one hand, and, the upper and lower support blocks, on the other hand. In this horizontal injection molding machine, the columns are subjected to weight torque and torsion torque, in particular when using heavy mold half carriers. Because the moving platen is displaced via the columns, loading of the columns with weight and torsion torques has also an adverse affect on the movement mechanism and the travel for the moving platen.
DE 19733667 A1 discloses a three-platen horizontal injection molding machine with a moving platen which extends between a fixed platen and a support platen and which is longitudinally displaceable in the fixed upper and lower columns. A rotary device provided for mold halves of injection molding tools and displaceable parallel to the longitudinal machine axis, is provided between the platens. In this horizontal injection molding machine, the rotary device has upper and lower support blocks which are supported and guided on the columns. A mold half carrier is rotatably received between the support blocks by an upper and lower pivot pin arranged on an axis and in suitable bearings. For moving the mold half carrier along the longitudinal machine axis, hydraulic actuators are provided between the moving platen and the upper and lower support blocks. In this type of three-platen horizontal injection molding machine, the lower columns are under stress because they have to support the substantial weight of the mold half carriers. When heavy mold half carriers are involved, there is a need to prop up the lower support block with rollers and/or skids on the machine bed.
WO 99/28108 discloses a three-platen injection molding machine having two pivot pins provided with several channels or passageways for conducting media, such as gases, liquids or electric current, to the mold half carriers and onward to the mold halves.
It would be desirable and advantageous to provide an improved horizontal injection molding machine which obviates prior art shortcomings and yet is simple in structure and reliable in operation.